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            "questionId": "913",
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            "title": "Random Flip Matrix",
            "titleSlug": "random-flip-matrix",
            "content": "<p>There is an <code>m x n</code> binary grid <code>matrix</code> with all the values set <code>0</code> initially. Design an algorithm to randomly pick an index <code>(i, j)</code> where <code>matrix[i][j] == 0</code> and flips it to <code>1</code>. All the indices <code>(i, j)</code> where <code>matrix[i][j] == 0</code> should be equally likely to be returned.</p>\n\n<p>Optimize your algorithm to minimize the number of calls made to the <strong>built-in</strong> random function of your language and optimize the time and space complexity.</p>\n\n<p>Implement the <code>Solution</code> class:</p>\n\n<ul>\n\t<li><code>Solution(int m, int n)</code> Initializes the object with the size of the binary matrix <code>m</code> and <code>n</code>.</li>\n\t<li><code>int[] flip()</code> Returns a random index <code>[i, j]</code> of the matrix where <code>matrix[i][j] == 0</code> and flips it to <code>1</code>.</li>\n\t<li><code>void reset()</code> Resets all the values of the matrix to be <code>0</code>.</li>\n</ul>\n\n<p>&nbsp;</p>\n<p><strong>Example 1:</strong></p>\n\n<pre>\n<strong>Input</strong>\n[&quot;Solution&quot;, &quot;flip&quot;, &quot;flip&quot;, &quot;flip&quot;, &quot;reset&quot;, &quot;flip&quot;]\n[[3, 1], [], [], [], [], []]\n<strong>Output</strong>\n[null, [1, 0], [2, 0], [0, 0], null, [2, 0]]\n\n<strong>Explanation</strong>\nSolution solution = new Solution(3, 1);\nsolution.flip();  // return [1, 0], [0,0], [1,0], and [2,0] should be equally likely to be returned.\nsolution.flip();  // return [2, 0], Since [1,0] was returned, [2,0] and [0,0]\nsolution.flip();  // return [0, 0], Based on the previously returned indices, only [0,0] can be returned.\nsolution.reset(); // All the values are reset to 0 and can be returned.\nsolution.flip();  // return [2, 0], [0,0], [1,0], and [2,0] should be equally likely to be returned.\n</pre>\n\n<p>&nbsp;</p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>1 &lt;= m, n &lt;= 10<sup>4</sup></code></li>\n\t<li>There will be at least one free cell for each call to <code>flip</code>.</li>\n\t<li>At most <code>1000</code> calls will be made to <code>flip</code> and <code>reset</code>.</li>\n</ul>\n",
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            "categoryTitle": "Algorithms",
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                    "lang": "C++",
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                    "code": "class Solution {\npublic:\n    Solution(int m, int n) {\n        \n    }\n    \n    vector<int> flip() {\n        \n    }\n    \n    void reset() {\n        \n    }\n};\n\n/**\n * Your Solution object will be instantiated and called as such:\n * Solution* obj = new Solution(m, n);\n * vector<int> param_1 = obj->flip();\n * obj->reset();\n */",
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                    "lang": "Java",
                    "langSlug": "java",
                    "code": "class Solution {\n\n    public Solution(int m, int n) {\n        \n    }\n    \n    public int[] flip() {\n        \n    }\n    \n    public void reset() {\n        \n    }\n}\n\n/**\n * Your Solution object will be instantiated and called as such:\n * Solution obj = new Solution(m, n);\n * int[] param_1 = obj.flip();\n * obj.reset();\n */",
                    "__typename": "CodeSnippetNode"
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                    "lang": "Python",
                    "langSlug": "python",
                    "code": "class Solution(object):\n\n    def __init__(self, m, n):\n        \"\"\"\n        :type m: int\n        :type n: int\n        \"\"\"\n        \n\n    def flip(self):\n        \"\"\"\n        :rtype: List[int]\n        \"\"\"\n        \n\n    def reset(self):\n        \"\"\"\n        :rtype: None\n        \"\"\"\n        \n\n\n# Your Solution object will be instantiated and called as such:\n# obj = Solution(m, n)\n# param_1 = obj.flip()\n# obj.reset()",
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                    "lang": "Python3",
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                    "code": "class Solution:\n\n    def __init__(self, m: int, n: int):\n        \n\n    def flip(self) -> List[int]:\n        \n\n    def reset(self) -> None:\n        \n\n\n# Your Solution object will be instantiated and called as such:\n# obj = Solution(m, n)\n# param_1 = obj.flip()\n# obj.reset()",
                    "__typename": "CodeSnippetNode"
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                    "lang": "C",
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                    "code": "\n\n\ntypedef struct {\n    \n} Solution;\n\n\nSolution* solutionCreate(int m, int n) {\n    \n}\n\nint* solutionFlip(Solution* obj, int* retSize) {\n  \n}\n\nvoid solutionReset(Solution* obj) {\n  \n}\n\nvoid solutionFree(Solution* obj) {\n    \n}\n\n/**\n * Your Solution struct will be instantiated and called as such:\n * Solution* obj = solutionCreate(m, n);\n * int* param_1 = solutionFlip(obj, retSize);\n \n * solutionReset(obj);\n \n * solutionFree(obj);\n*/",
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                    "lang": "C#",
                    "langSlug": "csharp",
                    "code": "public class Solution {\n\n    public Solution(int m, int n) {\n        \n    }\n    \n    public int[] Flip() {\n        \n    }\n    \n    public void Reset() {\n        \n    }\n}\n\n/**\n * Your Solution object will be instantiated and called as such:\n * Solution obj = new Solution(m, n);\n * int[] param_1 = obj.Flip();\n * obj.Reset();\n */",
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                    "lang": "JavaScript",
                    "langSlug": "javascript",
                    "code": "/**\n * @param {number} m\n * @param {number} n\n */\nvar Solution = function(m, n) {\n    \n};\n\n/**\n * @return {number[]}\n */\nSolution.prototype.flip = function() {\n    \n};\n\n/**\n * @return {void}\n */\nSolution.prototype.reset = function() {\n    \n};\n\n/** \n * Your Solution object will be instantiated and called as such:\n * var obj = new Solution(m, n)\n * var param_1 = obj.flip()\n * obj.reset()\n */",
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                    "code": "class Solution\n\n=begin\n    :type m: Integer\n    :type n: Integer\n=end\n    def initialize(m, n)\n        \n    end\n\n\n=begin\n    :rtype: Integer[]\n=end\n    def flip()\n        \n    end\n\n\n=begin\n    :rtype: Void\n=end\n    def reset()\n        \n    end\n\n\nend\n\n# Your Solution object will be instantiated and called as such:\n# obj = Solution.new(m, n)\n# param_1 = obj.flip()\n# obj.reset()",
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                    "lang": "Swift",
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                    "code": "\nclass Solution {\n\n    init(_ m: Int, _ n: Int) {\n        \n    }\n    \n    func flip() -> [Int] {\n        \n    }\n    \n    func reset() {\n        \n    }\n}\n\n/**\n * Your Solution object will be instantiated and called as such:\n * let obj = Solution(m, n)\n * let ret_1: [Int] = obj.flip()\n * obj.reset()\n */",
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                    "lang": "Go",
                    "langSlug": "golang",
                    "code": "type Solution struct {\n    \n}\n\n\nfunc Constructor(m int, n int) Solution {\n    \n}\n\n\nfunc (this *Solution) Flip() []int {\n    \n}\n\n\nfunc (this *Solution) Reset()  {\n    \n}\n\n\n/**\n * Your Solution object will be instantiated and called as such:\n * obj := Constructor(m, n);\n * param_1 := obj.Flip();\n * obj.Reset();\n */",
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                    "lang": "Scala",
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                    "code": "class Solution(_m: Int, _n: Int) {\n\n    def flip(): Array[Int] = {\n        \n    }\n\n    def reset() {\n        \n    }\n\n}\n\n/**\n * Your Solution object will be instantiated and called as such:\n * var obj = new Solution(m, n)\n * var param_1 = obj.flip()\n * obj.reset()\n */",
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                    "lang": "Kotlin",
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                    "code": "class Solution(m: Int, n: Int) {\n\n    fun flip(): IntArray {\n        \n    }\n\n    fun reset() {\n        \n    }\n\n}\n\n/**\n * Your Solution object will be instantiated and called as such:\n * var obj = Solution(m, n)\n * var param_1 = obj.flip()\n * obj.reset()\n */",
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                    "lang": "Rust",
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                    "code": "struct Solution {\n\n}\n\n\n/** \n * `&self` means the method takes an immutable reference.\n * If you need a mutable reference, change it to `&mut self` instead.\n */\nimpl Solution {\n\n    fn new(m: i32, n: i32) -> Self {\n        \n    }\n    \n    fn flip(&self) -> Vec<i32> {\n        \n    }\n    \n    fn reset(&self) {\n        \n    }\n}\n\n/**\n * Your Solution object will be instantiated and called as such:\n * let obj = Solution::new(m, n);\n * let ret_1: Vec<i32> = obj.flip();\n * obj.reset();\n */",
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                    "code": "class Solution {\n    /**\n     * @param Integer $m\n     * @param Integer $n\n     */\n    function __construct($m, $n) {\n        \n    }\n  \n    /**\n     * @return Integer[]\n     */\n    function flip() {\n        \n    }\n  \n    /**\n     * @return NULL\n     */\n    function reset() {\n        \n    }\n}\n\n/**\n * Your Solution object will be instantiated and called as such:\n * $obj = Solution($m, $n);\n * $ret_1 = $obj->flip();\n * $obj->reset();\n */",
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                    "lang": "TypeScript",
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                    "code": "class Solution {\n    constructor(m: number, n: number) {\n\n    }\n\n    flip(): number[] {\n\n    }\n\n    reset(): void {\n\n    }\n}\n\n/**\n * Your Solution object will be instantiated and called as such:\n * var obj = new Solution(m, n)\n * var param_1 = obj.flip()\n * obj.reset()\n */",
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                    "code": "defmodule Solution do\n  @spec init_(m :: integer, n :: integer) :: any\n  def init_(m, n) do\n\n  end\n\n  @spec flip() :: [integer]\n  def flip() do\n\n  end\n\n  @spec reset() :: any\n  def reset() do\n\n  end\nend\n\n# Your functions will be called as such:\n# Solution.init_(m, n)\n# param_1 = Solution.flip()\n# Solution.reset()\n\n# Solution.init_ will be called before every test case, in which you can do some necessary initializations.",
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